Originally Posted by techie

My semi-informed suspicion is that this is the point at which seating (and maybe something else too) is handed over to the team at the departure airport. I say semi-informed because one time I checked in about 5-10 mins after OLCI opened and found myself seat shifted (regular checks in the lead up had me in my original seat), but not due to curtain move, because my original row was still part of the cabin. A call to BAEC folks revealed at that around that time BA team at the departure airport can make seating changes for the usual myriad of reasons. I could be completely wrong, but felt confident enough to at least throw it into the hat.